Determine image dimensions

[ancarda]

Given a small chunk of the bytes (e.g. 0-8192), the headers for JPEG, GIF, PNG, and WebP, and eventually others, could be parsed and the dimensions understood. This function could look like:

public function determineDimensions($fh): array

Where array is a array of integers containing [width, height], for example [8, 32] for an 8x32 image.

[peter279k]

@ancarda, consider the following approach:

public function determineDimensions(string $filePath): array
{
    list($width, $height) = getimagesize('/path/to/image');

    return [$width, $height];
}

Is this proper way to solve this issue? Thanks.

[ancarda]

Hey,

Yeah, that would work for a prototype, although as a final implementation, one may as well just call getimagesize directly. While I'm quite sure getimagesize will work for just the first, e.g. 8K of an image (so it's parsing just the headers), I don't think it can work for streams as the API seems to expect a filepath.

It would be really crappy to accept a stream / SplFileInfo and have to write it out to disk so we can call getimagesize. By working with streams, any in-memory data can be inspected.

There might be a way around this, I will have a think... 🤔

[peter279k]

I think we need some approaches to detect the mime type in streams. Right?

[ancarda]

I imagine we’d use a similar approach, although once we know it’s some filetype, start trying to look for bytes that would record image height and width. Read that from the file header and return it.

Although this is lower priority, it would just be interesting to write such a function.

[peter279k]

This issue I think it can be closed since the PR #8 has been merged.